Memory device including voids between control gates

ABSTRACT

Some embodiments include apparatuses and methods of forming the apparatuses. One of the apparatuses includes a channel to conduct current, the channel including a first channel portion and a second channel portion, a first memory cell structure located between a first gate and the first channel portion, a second memory cell structure located between a second gate and the second channel portion, and a void located between the first and second gates and between the first and second memory cell structures.

PRIORITY APPLICATION

This application is a continuation of U.S. application Ser. No.16/863,117, filed Apr. 30, 2020, which is a continuation of U.S.application Ser. No. 16/197,217, filed Nov. 20, 2018, now issued as U.S.Pat. No. 10,644,105, which is a divisional of U.S. application Ser. No.15/675,130, now issued as U.S. Pat. No. 10,164,009, all of which areincorporated herein by reference in their entirety.

BACKGROUND

Memory devices are widely used in computers and many other electronicitems to store information. A memory device usually has numerous memorycells. Some conventional memory devices (e.g., three-dimensional (3D)flash memory devices) have memory cells arranged in tiers, in which thetiers are vertically stacked over a semiconductor substrate. Storagecapacity and performance are key features of such memory devices.However, the structures of many conventional memory cells and tiers makeimprovements associated with device storage capacity and performancedifficult. As described in more detail below, the memory devicespresented herein include structures that allow them to have improvementsover some conventional memory devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of an apparatus in the form of a memorydevice, according to some embodiments described herein.

FIG. 2A shows a block diagram of a portion of a memory device, accordingto some embodiments described herein.

FIG. 2B shows a schematic diagram of the portion of the memory device ofFIG. 2A, according to some embodiments described herein.

FIG. 2C shows a schematic diagram of a portion of memory device of FIG.2A and FIG. 2B, according to some embodiments described herein.

FIG. 2D shows a side view (cross-sectional views) of a structure of aportion of the memory device of FIG. 2C, according to some embodimentsdescribed herein.

FIG. 2E shows a portion of the memory device of FIG. 2D taken along line2E-2E of FIG. 2D, according to some embodiments described herein.

FIG. 3A, FIG. 3B, FIG. 3C, FIG. 3D, and FIG. 3E show side views ofstructures of portions of different memory devices having voids (e.g.,empty spaces that can contain air (air-filled voids) or gas (gas-filledvoids) and dielectric memory elements, according to some embodimentsdescribed herein.

FIG. 4A and FIG. 4B show side views of structures of portions ofdifferent memory devices having voids and polysilicon memory elements,according to some embodiments described herein.

FIG. 5A and FIG. 5B show side views of structures of portions ofdifferent memory devices that can be variations of the memory devices ofFIG. 4A and FIG. 4B, according to some embodiments described herein.

FIG. 6A through FIG. 6O show cross-sectional views of elements duringprocesses of forming a memory device that can be the memory device ofFIG. 3A, according to some embodiments of the invention.

FIG. 7A and FIG. 7B show cross-sectional views of elements duringprocesses of forming a memory device that can be the memory device ofFIG. 3B, according to some embodiments of the invention.

FIG. 8A and FIG. 8B show cross-sectional views of elements duringprocesses of forming a memory device that can be the memory device ofFIG. 3C, according to some embodiments of the invention.

FIG. 9A and FIG. 9B show cross-sectional views of elements duringprocesses of forming a memory device that can be the memory device ofFIG. 3D, according to some embodiments of the invention.

FIG. 10A, FIG. 10B, and FIG. 10C show cross-sectional views of elementsduring processes of forming a memory device that can be the memorydevice of FIG. 3E, according to some embodiments of the invention.

FIG. 11A through FIG. 11P show cross-sectional views of elements duringprocesses of forming a memory device that can be the memory device ofFIG. 4A, according to some embodiments of the invention.

FIG. 12A and FIG. 12B show cross-sectional views of elements duringprocesses of forming a memory device that can be the memory device ofFIG. 4B, according to some embodiments of the invention.

FIG. 13 shows cross-sectional views of elements during processes offorming a memory device that can be the memory device of FIG. 5A,according to some embodiments of the invention.

FIG. 14 shows cross-sectional views of elements during processes offorming a memory device that can be the memory device of FIG. 5B,according to some embodiments of the invention.

FIG. 15 is a flow chart showing processes of forming a memory deviceincluding voids between gates and between memory cell structures,according to some embodiments described herein.

DETAILED DESCRIPTION

FIG. 1 shows a block diagram of an apparatus in the form of a memorydevice 100, according to some embodiments described herein. Memorydevice 100 can include a memory array (or multiple memory arrays) 101containing memory cells 110. In the physical structure of memory device100, memory cells 110 can be arranged vertically (e.g., stacked overeach other) over a substrate of memory device 100 (e.g., a semiconductorsubstrate of an IC chip that includes memory device 100). Memory cells110 can include non-volatile cells. Memory cells 110 can have differentnon-volatile memory cell types. For example, memory cells 110 can becharge trap memory cells (e.g., charge trap flash), floating gate memorycells, or other types of non-volatile memory cells.

As shown in FIG. 1, memory cells 110 can be arranged in blocks (memorycell blocks), such as blocks 101A and 101B. Each of blocks 101A and 101Bcan include sub-blocks. For example, block 101A can include sub-blocks101A₀ and 101A_(n), and block 101B can include sub-blocks 101B₀ and101B_(n). Each of sub-blocks 101A₀, 101A_(n), 101B₀, and 101B_(n) caninclude multiple memory cells 110. FIG. 1 shows memory device 100 havingtwo blocks 101A and 101B and two sub-blocks in each of the blocks as anexample. Memory device 100 can have more than two blocks and more thantwo sub-blocks in each of the blocks.

As shown in FIG. 1, memory device 100 can include access lines (whichcan include word lines) 150 and data lines (which can include bit lines)170. Access lines 150 can carry signals (e.g., word line signals) WL0through WLm. Data lines 170 can carry signals (e.g., bit line signals)BL0 through BLn. Memory device 100 can use access lines 150 toselectively access sub-blocks 101A₀, 101A_(n), 101B₀, and 101B_(n) ofblocks 101A and 101B and data lines 170 to selectively exchangeinformation (e.g., data) with memory cells 110 of blocks 101A and 101B.

Memory device 100 can include an address register 107 to receive addressinformation (e.g., address signals) ADDR on lines (e.g., address lines)103. Memory device 100 can include row access circuitry 108 and columnaccess circuitry 109 that can decode address information from addressregister 107. Based on decoded address information, memory device 100can determine which memory cells 110 of which sub-blocks of blocks 101Aand 101B are to be accessed during a memory operation. Memory device 100can perform a read operation to read (e.g., sense) information (e.g.,previously stored information) in memory cells 110, or a write (e.g.,program) operation to store (e.g., program) information in memory cells110. Memory device 100 can use data lines 170 associated with signalsBL0 through BLn to provide information to be stored in memory cells 110or obtain information read (e.g., sensed) from memory cells 110. Memorydevice 100 can also perform an erase operation to erase information fromsome or all of memory cells 110 of blocks 101A and 101B.

Memory device 100 can include a control unit 118 (which can includecomponents such as a state machine (e.g., finite state machine),register circuits, and other components) configured to control memoryoperations (e.g., read, write, and erase operations) of memory device100 based on control signals on lines 104. Examples of the controlsignals on lines 104 include one or more clock signals and other signals(e.g., a chip enable signal CE #, a write enable signal WE #) toindicate which operation (e.g., read, write, or erase operation) memorydevice 100 can perform.

Memory device 100 can include sense and buffer circuitry 120 that caninclude components such as sense amplifiers and page buffer circuits(e.g., data latches). Sense and buffer circuitry 120 can respond tosignals BL_SEL0 through BL_SELn from column access circuitry 109. Senseand buffer circuitry 120 can be configured to determine (e.g., bysensing) the value of information read from memory cells 110 (e.g.,during a read operation) of blocks 101A and 101B and provide the valueof the information to lines (e.g., global data lines) 175. Sense andbuffer circuitry 120 can also can be configured to use signals on lines175 to determine the value of information to be stored (e.g.,programmed) in memory cells 110 of blocks 101A and 101B (e.g., during awrite operation) based on the values (e.g., voltage values) of signalson lines 175 (e.g., during a write operation).

Memory device 100 can include input/output (I/O) circuitry 117 toexchange information between memory cells 110 of blocks 101A and 101Band lines (e.g., I/O lines) 105. Signals DQ0 through DQN on lines 105can represent information read from or stored in memory cells 110 ofblocks 101A and 101B. Lines 105 can include nodes within memory device100 or pins (or solder balls) on a package where memory device 100 canreside. Other devices external to memory device 100 (e.g., a memorycontroller or a processor) can communicate with memory device 100through lines 103, 104, and 105.

Memory device 100 can receive a supply voltage, including supplyvoltages Vcc and Vss. Supply voltage Vss can operate at a groundpotential (e.g., having a value of approximately zero volts). Supplyvoltage Vcc can include an external voltage supplied to memory device100 from an external power source such as a battery or alternatingcurrent to direct current (AC-DC) converter circuitry.

Each of memory cells 110 can be programmed to store informationrepresenting a value of at most one bit (e.g., a single bit), or a valueof multiple bits such as two, three, four, or another number of bits.For example, each of memory cells 110 can be programmed to storeinformation representing a binary value “0” or “1” of a single bit. Thesingle bit per cell is sometimes called a single-level cell. In anotherexample, each of memory cells 110 can be programmed to store informationrepresenting a value for multiple bits, such as one of four possiblevalues “00”, “01”, “10”, and “11” of two bits, one of eight possiblevalues “000”, “001”, “010”, “011”, “100”, “101”, “110”, and “111” ofthree bits, or one of other values of another number of multiple bits. Acell that has the ability to store multiple bits is sometimes called amulti-level cell (or multi-state cell).

Memory device 100 can include a non-volatile memory device, such thatmemory cells 110 can retain information stored thereon when power (e.g.,voltage Vcc, Vss, or both) is disconnected from memory device 100. Forexample, memory device 100 can be a flash memory device, such as a NANDflash (e.g., 3-dimensional (3-D) NAND (e.g., vertical NAND)) or a NORflash memory device, or another kind of memory device, such as avariable resistance memory device (e.g., a phase change memory device ora resistive RAM (Random Access Memory) device). One of ordinary skill inthe art may recognize that memory device 100 may include othercomponents, several of which are not shown in FIG. 1 so as not toobscure the example embodiments described herein.

At least a portion of memory device 100 (e.g., a portion of memory array101) can include structures similar to or identical to the any of thememory devices described below with reference to FIG. 2A through FIG.14.

FIG. 2A shows a block diagram of a portion of a memory device 200including a memory array 201 having memory cell strings 231 through 240,240′, and 240″, select circuits 241 through 252 and 241′ through 252′,according to some embodiments described herein. Memory device 200 cancorrespond to memory device 100 of FIG. 1. For example, memory array 201can form part of memory array 101 of FIG. 1.

As shown in FIG. 2A, memory device 200 can include blocks (memory cellblocks) 201A and 201B. Two blocks are shown as an example. Memory device200 can include many blocks (e.g., up to thousands or more blocks). Eachof blocks 201A and 201B can have sub-blocks. For example, block 201A hassub-block 201A₀ and 201A_(n), and block 201B has sub-block 201B₀ and201B_(n). Two sub-blocks (e.g., index n=1) are shown in each of blocks201A and 201B as an example. Each of blocks 201A and 201B can have morethan two sub-blocks (e.g., n>1).

As shown in FIG. 2A, block 201A can include memory cell strings 231through 236, select circuits 241 through 246 and 241′ through 246′.Block 201B can include memory cell strings 237 through 240, 240′, and240″, and select circuits 247 through 252 and 247′ through 252′. Each ofmemory cell strings 231 through 240, 240′, and 240″ has memory cells(e.g., memory cells 210, 211, 212, and 213 shown in FIG. 2B) that arearranged in a string (e.g., memory cells coupled in series among eachother) to store information. During an operation (e.g., write or read)of memory device 200, memory cell strings 231 through 240, 240′, and240″ and their associated select circuits can be individually selectedto access the memory cells (e.g., memory cells 210, 211, 212, and 213shown in FIG. 2B) in the selected memory cell string in order to storeinformation in or read information from the selected memory cell string.During an erase operation, all of the memory cell strings in aparticular sub-block (or in particular sub-blocks) can be selected(e.g., concurrently selected) to erase information from them.

As shown in FIG. 2A, each of the memory cell strings 231 through 240,240′, and 240″ can be associated with (e.g., coupled to) two selectcircuits. For example, memory cell string 231 is associated with selectcircuit (e.g., top select circuit) 241 and select circuit (e.g., bottomselect circuit) 241′. FIG. 2A shows an example of six memory cellstrings (e.g., strings 231 through 236, or strings 237 through 240, and240′ and 240″) and their associated circuits (e.g., top and bottomselect circuits) in each of blocks 201A and 201B. The number of memorycell strings and their associated select circuits in each of blocks 201Aand 201B can vary.

As shown in FIG. 2A, memory device 200 can include data lines 270, 271,and 272 that carry signals BL0, BL1, and BL2, respectively. Each of datalines 270, 271, and 272 can be structured as a conductive line that caninclude bit lines of memory device 200. The memory cell strings ofblocks 201A and 201B can share data lines 270, 271, and 272. Forexample, memory cell strings 231, 232 (of block 201A), 237, 238 (ofblock 201B) can share data line 270. Memory cell strings 233, 234 (ofblock 201A), 239, 240 (of block 201B) can share data line 271. Memorycell strings 235, 236 (of block 201A), 240′, 240″ (of block 201B) canshare data line 272. FIG. 2A shows three lines (e.g., data lines) 270,271, and 272 as an example. The number of data lines of memory device200 can vary.

Memory device 200 can include a line 292 that can carry a signal SRC(e.g., source line signal). Line 292 can be structured as a conductiveline (or a conductive region (e.g., source region)) and can form part ofa source (e.g., a source line or a source region) of memory device 200.As shown in FIG. 2A, blocks 201A and 201B can share line 292.

Memory device 200 can include separate gates (e.g., control gates) inblocks 201A and 201B. For example, memory device 200 can include gates283 in block 201A that can carry corresponding signals (e.g., word linesignals) WL0 ₀, WL1 ₀, WL2 ₀, and WL3 ₀; and gates 283 in block 201Bthat can carry corresponding signals (e.g., word line signals) WL0 ₁,WL1 ₁, WL2 ₁, and WL3 ₁. Gates 283 of block 201A are not electricallycoupled to each other. Gates 283 of block 201B are not electricallycoupled to each other. Gates 283 of block 201A are not electricallycoupled to gates 283 of block 201B. FIG. 2A shows four gates 283 in eachof blocks 201A and 201B as an example. The number of gates of memorydevice 200 can vary.

Each of gates 283 of block 201A and 201B can be structured as aconductive gate. Gates 283 can form part of respective access lines(e.g., part of word lines) of memory device 200 to access memory cellsof memory cell strings 231 through 240, 240′, and 240″ in a respectiveblock. For example, during a read or write operation to storeinformation in or read information from a memory cell (or memory cells)in block 201A, gates 283 of block 201A can be activated (e.g., providedwith positive voltages) to access a selected memory cell (or selectedmemory cells) in block 201A. In the example here, gates 283 of block201B can be deactivated (e.g., provided with zero volts (e.g., ground))when gates 283 of block 201A are activated. In memory device 200, blocks201A and 201B (which share the same data lines 270, 271, and 272) can beaccessed (e.g., accessed during a read or write operation) one block ata time.

As shown in FIG. 2A, memory device 200 can include select lines (e.g.,drain select lines) 280 ₀ and 280 _(n) in block 201A and select lines(e.g., drain select lines) 281 ₀ and 281 _(n) in block 201B. Each ofselect lines 280 ₀, 280 _(n), 281 ₀, and 281 _(n) can carry a differentsignal (SGD₀ or SGD_(n)). FIG. 2A shows blocks 201A and 201B havingsignals with the same names (e.g., SGD₀ or SGD_(n)) for simplicity.However, signals SGD₀ and SGD_(n) of one block (e.g., block 201A) aredifferent from signals SGD₀ and SGD_(n) of another block (e.g., block201B).

In block 201A, select circuits 241, 243, and 245 can share select line280 ₀, and select circuits 242, 244, and 246 can share select line 280_(n). In block 201B, select circuits 247, 249, and 251 can share selectline 281 ₀, and select circuits 248, 250, and 252 can share select line281 _(g). Each of select circuits 241 through 252 in blocks 201A and201B can include a select transistor (shown in FIG. 2B) that can becontrolled (e.g., turned on or turned off) by a respective select line(e.g., select line 280 ₀, 280 _(n), 281 ₀, or 281 _(n)).

Memory device 200 can include a select line (e.g., source select line)280′ in block 201A, and a select line (e.g., source select line) 281′ inblock 201B. Each of select lines 280′ and 281′ can carry a signal SGS.Signal SGS of one block (e.g., block 201A) can be different from signalSGS of another block (e.g., block 201B). FIG. 2A shows select lines 280′and 281′ separated from each other as an example. However, select lines280′ and 281′ can be coupled to each other, such that blocks 201A and201B can share signal SGS.

In block 201A, select circuits 241′, 242′, 243′, 244′, 245′, and 246′can share select line 280′. In block 201B, select circuits 247′, 248′,249′, 250′, 251′, and 252′ can share select line 281′. Each of selectcircuits 241′ through 252′ in blocks 201A and 201B can include a selecttransistor (shown in FIG. 2B) that can be controlled (e.g., turned on orturned off) by a respective select line (e.g., select line 280′ or281′).

During an operation of memory device 200, one or both select circuitsassociated with a selected memory cell string can be activated (e.g., byturning on the transistors in the select circuits), depending on whichoperation memory device 200 performs on the selected memory cell string.During a write operation of memory device 200, memory device 200 canconcurrently select memory cells of memory cell strings of sub-blocks ofa selected block in order to store information in (e.g., during a writeoperation) the selected memory cells. During a read operation of memorydevice 200, memory device 200 can select a block as a selected block toread information from memory cells of the selected block. During anerase operation, memory device 200 can select a block as a selectedblock to erase information from memory cells in a portion (e.g., asub-block or multiple sub-blocks) of the selected block or memory cellsfrom the entire selected block.

Activating a particular select circuit among select circuits 241 through252 during an operation of memory device 200 can include providing(e.g., applying) voltages having certain values to signals SGD₀ andSGD_(n) associated with that particular select circuit. Activating aparticular select circuit among select circuits 241′ through 252′ caninclude providing (e.g., applying) voltages having certain values tosignal SGS associated with that particular select circuit.

FIG. 2B shows a schematic diagram of a portion of memory device 200 ofFIG. 2A, according to some embodiments described herein. For simplicity,only four of the memory cell strings (memory cell strings 231, 232, 237and 238) are labeled, only four of the top select circuits (241, 242,247, and 248) are labeled, and only four of the bottom select circuits(241′, 242′, 247′, and 248′) are labeled.

As shown in FIG. 2B, memory device 200 can include memory cells 210,211, 212, and 213 that can be physically arranged in three dimensions(3-D), such as x, y, and z dimensions of memory device 200. Memory cells210, 211, 212, and 213 can correspond to memory cells 110 of FIG. 1.Thus, memory cells 210, 211, 212, and 213 can include non-volatilememory cells (e.g., charge trap memory cells, floating gate memorycells, or other types of non-volatile memory cells). Each of the memorycell strings (e.g., strings 231, 232, 237 and 238) can include one ofmemory cells 210, one of memory cells 211, one of memory cells 212, andone of memory cells 213 coupled in series among each other. FIG. 2Bshows an example where memory device 200 has four levels (e.g., fourtiers) of respective memory cells 210, 211, 212, and 213, and fourmemory cells in each of the memory cell strings. The number of levels(e.g., tiers) of memory cells, and the number of memory cells in eachmemory cell string, can vary.

As shown in FIG. 2B, memory device 200 can include select transistors(e.g., drain select transistors) 261 and select transistors (e.g.,source select transistors) 262 associated with select lines 280 ₀, 280_(n), 281 ₀, 281 _(n), 280′, and 281′. In memory device 200, a selectline (e.g., select line 280 ₀, 280 _(n), 281 ₀, 281 _(n), 280′, or 281′)can include a conductive material to carry a signal (e.g., signal SGD₀,SGD_(n), or SGS). A select line (e.g., select line 280 ₀, 280 _(n), 281₀, 281 _(n), 280′, or 281′) does not operate like a switch (e.g., atransistor). A select transistor (e.g., select transistor 261 or 262)can receive a signal from a respective select line and can operate likea switch.

Select transistor 261 or select transistor 262, or both, can include astructure that is similar to or identical to the structure of memorycells 210, 211, 212, and 213. Alternatively, select transistor 261 or262, or both, can include a structure different from the structure ofmemory cells 210, 211, 212, and 213. For example, select transistor 261or 262, or both, can have a field-effect transistor (EFT) structure,such as metal-oxide semiconductor (MOS) structure.

FIG. 2B shows each of the top select circuits (e.g., select circuits241, 242, 247, and 248) and each of bottom select circuits (e.g., selectcircuits 241′, 242′, 247′, and 248′) of memory device 200 as includingone transistor (e.g., select transistor 261 or 262) as an example.However, each of the top and bottom select circuits of memory device 200can include multiple series-connected transistors. Further, the numberof transistors (e.g., either multiple transistors or a singletransistor) in each of the top select circuits can be different from thenumber of transistors (e.g., either multiple transistors or a singletransistor) in each of the bottom select circuits.

FIG. 2C shows a schematic diagram of a portion of memory device 200 ofFIG. 2A and including memory cell string 231 and associated selectcircuits (e.g., top select circuit 241 and bottom select circuit 241′),according to some embodiments described herein. The portion of memorydevice 200 in FIG. 2C is also shown in FIG. 2B. FIG. 2C also shows line(e.g., data line) 270 and corresponding signal BL0, line (e.g., source)292 and corresponding signal SRC, and gates 283 and correspondingsignals WL0 ₀, WL1 ₀, WL2 ₀, and WL3 ₀.

FIG. 2D shows a side view of a structure of a portion of memory device200 (e.g., the portion schematically shown in and FIG. 2C), according tosome embodiments described herein. For simplicity, the structures ofonly memory cells 210, 211, 212, and 213 of memory cell string 231 ofmemory device 200 are shown in FIG. 2D. The structures of memory cells210, 211, 212, and 213 of other memory cell strings (schematically shownin FIG. 2A and FIG. 2B) of memory device 200 can be similar to oridentical to the structures of memory cells 210, 211, 212, and 213 ofmemory cell string 231 shown in FIG. 2D. Also for simplicity,cross-sectional lines (e.g., hatch lines) are omitted from most of theelements shown in the drawings described herein.

As shown in FIG. 2D, memory device 200 can include a substrate 299 overwhich memory cells 210, 211, 212, and 213 can be formed (e.g., formedvertically with respect to substrate 299). Memory device 200 includesdifferent levels 202 through 208 with respect to a z-dimension. Levels202 through 208 are internal device levels between substrate 299 anddata line 270 of memory device 200. As shown in FIG. 2D, memory cells210, 211, 212, and 213 can be located (e.g., located vertically withrespect to substrate 299) in levels 202, 204, 206, and 208,respectively.

Gates 283 (associated with memory cells 210, 211, 212, and 213,respectively) can also be located (e.g., located vertically with respectto substrate 299) in levels 202, 204, 206, and 208, respectively. Selectlines 280 ₀ can be located in a level between the level of data line 270and level 208. Select line 280′ can be located in a level between level202 and substrate 299.

Substrate 299 can include monocrystalline (also referred to assingle-crystal) semiconductor material. For example, substrate 299 caninclude monocrystalline silicon (also referred to as single-crystalsilicon). The monocrystalline semiconductor material of substrate 299can include impurities, such that substrate 299 can have a specificconductivity type (e.g., n-type or p-type). Substrate 299 can includecircuitry 298 formed in substrate 299. Circuitry 298 can include senseamplifiers and page buffer circuits (that can be similar to sense andbuffer circuitry 120 of FIG. 1), decoder circuitry (that can be similarto row and column access circuitry 108 and 109 of FIG. 1), and othercircuitry. As shown in FIG. 2D, memory cells 210, 211, 212, and 213, andgates 283, can be formed (e.g., formed vertically in the z-direction)over circuitry 298 and substrate 299.

As shown in FIG. 2D, data line 270 can have length in the x-direction,which is perpendicular to the z-dimension. Line 292 (e.g., sourceregion) can include a conductive material (e.g., a conductive region)and can be formed over a portion of substrate 299 (e.g., by depositing aconductive material over substrate 299). Alternatively, line 292 can beformed in or formed on a portion of substrate 299 (e.g., by doping aportion of substrate 299). Memory device 200 can include dielectricmaterials (e.g., silicon oxide) 288 between each of data line 270 andline 292 and other components of memory device 200.

As shown in FIG. 2D, memory device 200 can include a pillar (conductivepillar) 255 having lengths extending in a direction perpendicular to(e.g., a vertical direction in the z-direction of memory device 200) aconductive material region of line 292 and substrate 299. Pillar 255 caninclude a channel 280M, portions 256 and 257 (e.g., conductive contact(plug) regions), and portion 258 (e.g., a center region of pillar 255).Portion 256 can contact data line 270. Portion 257 can contact aconductive region of line 292. Portion 258 can be either a hollowportion (e.g., an empty portion) or a solid portion (e.g., a portionhaving either a dielectric material or a conductive material). Portion258 can be surrounded by channel 280M.

Channel 280M is part of a conductive path (e.g., current path formed bychannel 280M and portions 256 and 257) of pillar 255. The conductivepath can carry current (e.g., current between data line 270 and line 292(e.g., source)) during an operation (e.g., read, write, or erase) ofmemory device 200. In an alternative structure of pillar 255, portion258 may be omitted and channel 280M may contact (directly couple to) aconductive region of line 292. FIG. 2D shown an example where each ofportions 256, 257, 258, and 280 have a specific dimension (e.g., length)in the z-direction. However, the dimension of each of portions 256, 257,258, and 280 can vary.

As shown in FIG. 2D, memory cells 210, 211, 212, and 213 of memory cellstring 231 can be located along different segments of pillar 255 (e.g.,different segments of pillar 255 extending from level 202 to level 208).In a similar structure (not shown in FIG. 2D), memory cells 210, 211,212, and 213 of other memory cell strings of memory device 200 can belocated along different segments of other pillars (not shown) of memorydevice 200.

As shown in FIG. 2D, gates 283 (associated with respective memory cells210, 211, 212, and 213) can also be located along pillar 255 at the samesegments (e.g., the segment extending from level 202 to level 208) wherememory cells 210, 211, 212, and 213 are located. Each of gates 283 canbe used to access the memory cell (or memory cells) on a respectivelevel. For example, gate 283 associated with signal WL0 ₃ can be used toaccess the memory cells (e.g., memory cell 213), and gate 283 associatedwith signal WL0 ₂ can be used to access the memory cells (e.g., memorycell 212).

As shown in FIG. 2D, each of memory cells 210, 211, 212, and 213 caninclude a memory cell structure 219 located between a respective gateamong gates 283 and a channel portion (a portion of channel 280M). Forexample, memory cell 213 can include memory cell structure 219 locatedbetween one of gates 283 (gate 283 associated with signal WL0 ₃) andchannel portion 280.1, and memory cell 212 can include memory cellstructure 219 located between one of gates 283 (gate 283 associated withsignal WL0 ₂) and channel portion 280.2.

Each of select transistors 261 and 262 can include a select transistorstructure 219′. Select transistor structure 219′ can be similar to oridentical to memory cell structure 219. Alternatively, select transistorstructure 219′ can be a MOS transistor-type structure that is differentfrom memory cell structure 219. A cross section (e.g., top view) ofmemory device 200 including a portion of memory cell structure 219(taken along section line 2E-2E) is described below with reference toFIG. 2E.

As shown in FIG. 2D, memory device 200 can include voids 285 located atdifferent locations between components (e.g., gates 283 and memory cellstructures 219) of memory cells 210, 211, 212, and 213. Each of voids285 is an empty space that can contain air (an air-filled void (e.g., anair gap)) or gas (a gas-filled void).

A void among voids 285 can be located (e.g., can occupy a location)between two adjacent gates 283 and between two adjacent memory cellstructures 219. Two adjacent gates are two gates located immediatelynext to each other. Two adjacent memory cell structures are memory cellstructures located immediately next to each other. For example, FIG. 2Dshows one of voids 285 located between adjacent gates 283 associatedwith signals WL0 ₂ and WL0 ₃ and between adjacent memory cell structures219 of memory cells 212 and 213.

As shown in FIG. 2D, a void among voids 285 can be located (e.g., canoccupy a location) between a particular select line (e.g., select line280 ₀ or 280′) and an adjacent gate among gates 283, and between aselect transistor structure 219′ and an adjacent memory cell structure219. For example, FIG. 2D shows one of voids 285 located between selectline 280 ₀ a gate 283 associated with signals WL0 ₃ and between selecttransistor structure 219′ of select transistor 261 and memory cellstructure 219 of memory cell 213.

FIG. 2D shows an example where some channel portions (e.g., channelportion 280.3) of channel 280M are exposed to voids 285. However, pillar255 can include a dielectric material between a respective channelportion (e.g., channel portion 280.3) of channel 280M, such that channel280M is not exposed to voids 285.

In an alternative structure of memory device 200, some of voids 285 maybe omitted. For example, memory device 200 may not include (may exclude)top and bottom voids 285 (e.g., a void between select line 280 ₀ andgate 283 associated with signal WL0 ₃, and an void between select lineselect line 280′ and gate 283 associated with signal WL0 ₀.

In another alternative structure of memory device 200, all of voids 285may be omitted. For example, memory device 200 may not include (mayexclude) voids 285, such that the locations that are occupied by voids285 can include a dielectric material (e.g., a dielectric oxide, adielectric nitride, or other dielectric materials).

As shown in FIG. 2D, memory device 200 can include sealing dielectric287 (e.g., dielectric oxide), which seals off voids 285 in memory device200. Thus, each of voids 285 can be contained within a region bounded(e.g., surrounded) by sealing dielectric 287, two adjacent gates 283 (orone gate 283 and a select line (select line 280 ₀ or 280′)), twoadjacent memory cell structures 219 (or one memory cell structure 219and one select transistor structure 219′), and a respective channelportion (e.g., channel portion 280.3) of channel 280M.

In FIG. 2D, memory cell structure 219 can be any of the memory cellstructures described below with reference to FIG. 2E, FIG. 3A throughFIG. 3E, FIG. 4A, FIG. 4B, FIG. 5A, and FIG. 5B.

FIG. 2E shows a portion of memory device 200 along line 2E-2E of FIG. 2Dincluding memory cell structure 219 of memory cell 213, according tosome embodiments described herein. As shown in FIG. 2E, memory cellstructure 219 is located between gate 283 (associated with signal WL0 ₃)and channel 280M. Memory cell structure 219 can also be surround by gate283. Memory cell structure 219 can include a dielectric barrier (e.g., adielectric region) 242M, a dielectric blocking region 252M, a memoryelement 262M, and a tunnel region 276M. For simplicity, only memoryelement 262M has cross-sectional lines (e.g., hatch lines).Cross-sectional lines are omitted from other elements of memory device200 shown in FIG. 2E. Similar to memory element 262M, only memoryelements (or part of the memory elements) of the memory devicesdescribed below (e.g., in FIG. 3A through FIG. 14) have cross-sectionallines.

In FIG. 2E, gate 283 can be a metal gate. For example, gate 283 can be atungsten gate contacting dielectric barrier 242M. Alternatively, gate283 can include a combination of metals and metallic compounds. Forexample, gate 283 can include a conductive titanium nitride regioncontacting dielectric barrier 242M, and a metal (e.g., tungsten)contacting the conductive titanium nitride region, such that theconductive titanium nitride region is between the metal and dielectricbarrier 242M. Other conductive materials can be used for gate 283.

Dielectric barrier 242M can include a high-k dielectric material or acombination of high-k dielectric materials. A high-k dielectric materialis dielectric material that has a dielectric constant greater than thedielectric constant of silicon dioxide. One of the functions ofdielectric barrier 242M includes shielding (e.g., protecting) dielectricblocking region 252M from some processes (e.g., etch processes) duringthe processes of forming memory device 200. Dielectric barrier 242M caninclude aluminum oxide or other dielectric (dielectric material) havinga dielectric constant greater than the dielectric constant of aluminumoxide. As an example, dielectric barrier 242M can include aluminumoxide, hafnium oxide, or zirconium oxide. In another example, dielectricbarrier 242M can include a mixture of hafnium oxide with at least one ofaluminum oxide, silicon oxide, titanium oxide, gadolinium oxide, niobiumoxide, and tantalum oxide. In another example, dielectric barrier 242Mcan include a mixture of zirconium oxide with at least one of aluminumoxide, silicon oxide, titanium oxide, gadolinium oxide, niobium oxide,and tantalum oxide. In another example, dielectric barrier 242M caninclude a mixture of hafnium oxide and zirconium oxide with at least oneof aluminum oxide, silicon oxide, titanium oxide, gadolinium oxide,niobium oxide, and tantalum oxide. Other high-k dielectrics can be usedfor dielectric barrier 242M. Dielectric barrier 242M can have athickness (from gate 283 to dielectric blocking region 252M) in a rangefrom about 15 angstroms to about 50 angstroms.

Dielectric blocking region 252M includes a material different from thematerial of dielectric barrier 242M. Dielectric blocking region 252M isdisposed on and contacting dielectric barrier 242M. Dielectric blockingregion 252M provides a mechanism to block charge from flowing frommemory element 262M to gate 283. Dielectric blocking region 252M can bean oxide (e.g., silicon oxide) or other dielectric materials.

Memory element 262M can be configured to store information in memorycell 213. Memory element 262M can be a dielectric nitride region (e.g.,a region including dielectric silicon nitride). Other dielectricmaterials for memory element 262M can be used to trap charge.Alternatively, memory element 262M can be polycrystalline silicon(polysilicon). The value (e.g., the value representing one bit ormultiple bits) of information stored in memory cell 213 can be based onthe amount of charge (e.g., the number of electrons) in memory element262M. The amount of charge in memory element 262M can be controlled(e.g., increased or decreased) in part based on the value of voltage(e.g., carried by signal WL0 ₃) applied to gate 283, the value ofvoltage applied to channel 280M, or both values of voltages applied togate 283 and channel 280M. For example (e.g., in a write operation), thenumber of electrons in memory element 262M can be increased bycontrolling (e.g., increasing) the value of voltage applied to gate 283in order to cause some of the electrons from channel 280M to move (e.g.,tunnel) to memory element 262M (through tunnel region 276M). In anotherexample (e.g., in an erase operation), the number of electrons in memoryelement 262M can be decreased by controlling (e.g., decreasing) thevalue of voltage applied to gate 283 in order to some of the electronsfrom memory element 262M to move to channel 280M to (through tunnelregion 276M).

Tunnel region 276M can be constructed to allow tunneling (e.g.,transportation) of charge (e.g., electrons) between memory element 262Mand channel 280M. Tunnel region 276M can include an oxide (e.g., siliconoxide), a nitride (e.g., silicon nitride), or a combination of oxide andnitride. For example, tunnel region 276M can be a single (e.g., onlyone) dielectric (e.g., oxide). In another example, tunnel region 276Mcan include multiple dielectrics, which can be constructed as differentregions (e.g., layers) of dielectric materials. For example, tunnelregion 276M can include a dielectric nitride region (e.g., a layer ofsilicon nitride) sandwiched between two dielectric oxide regions (e.g.,two layers of silicon oxide).

Channel 280M can include semiconductor material. Example materials forchannel 280M include polysilicon (e.g., undoped or doped polysilicon).The polysilicon can be n-type or p-type polysilicon. As described above,channel 280M is part of a conductive path that can carry current duringan operation (e.g., read, write, or erase) of memory device 200.

Portion 258 can be either a hollow portion (e.g., an empty portion) or asolid portion (e.g., a portion having either a dielectric material or aconductive material). Thus, channel 280M can be a hollow channel (e.g.,if portion 258 is empty or filled with a non-conductive material (e.g.,dielectric oxide, such as silicon oxide).

Memory cell structure 219 shown in FIG. 2D and FIG. 2E is an examplememory cell structure of memory device 200. However, memory cellstructure 219 can be (or can include) any of memory cell structuresdescribed below with reference to FIG. 3A through FIG. 14. Thus, memorycell structure 219 can be substituted by any of the memory cellstructures described below with reference to FIG. 3A through FIG. 14.

FIG. 3A, FIG. 3B, FIG. 3C, FIG. 3D, FIG. 3E, FIG. 4A, FIG. 4B, FIG. 5A,and FIG. 5B show side views (cross-sectional views) of structures ofportions of respective memory devices 300A, 300B, 300C, 300D, 300E,400A, 400B, 500A, and 500B, according to some embodiments describedherein. The figures described herein give the same labels (e.g.,reference names and numbers) for similar or identical elements. Forsimplicity, the description herein refrains from repeating thedescriptions of similar or identical elements within the same memorydevice and among different memory devices. Also for simplicity, only aportion of each of the memory devices described below is shown in thedrawings. However, each of the memory devices described below withreference to FIG. 3A through FIG. 14 can include elements similar to oridentical to the elements of memory device 100 (FIG. 1) and 200 (FIG. 2Athrough FIG. 2E).

For example, the elements of memory device 300A above level 608 can besimilar to the elements above level 208 of memory device 200 in FIG. 2D.In another example, the elements of memory device 300A in portion 694(e.g., between level 602 and line (e.g., source) 692) can be similar toor identical to the elements in portion 294 of memory device 200 in FIG.2D.

As shown in FIG. 3A, memory device 300A can include a substrate 699,conductive region 692, and levels 602 through 608 (e.g., vertical levelin the z-direction, which is perpendicular to the x-direction (directionfrom channel 680 to gate 683)). Memory device 300A can include memorycells 610, 611, 612, and 613, gates 683 located in respective levels 602through 608, a channel 680 having a length extending through levels 602through 608 in the z-direction, and a portion 658. Memory device 300Acan include voids 685 located at levels 603, 605, and 607, and sealingdielectric 687 that seal off voids 685 in memory device 300A. Each ofvoids 685 is an empty space that can contain air (an air-filled void(e.g., an air gap)) or gas (a gas-filled void).

Each of memory cells 610, 611, 612, and 613 can include a memory cellstructure 619 a, which can be located between a respective gate (one ofgates 683) and a channel portion of channel 680. For example, memorycell 613 can include memory cell structure 619 a located between one ofgates 683 and channel portion 680.1, and memory cell 612 can includememory cell structure 619 a located between one of gates 683 and channelportion 680.2.

Each memory cell structures 619 a can include a dielectric barrier(e.g., a dielectric region) 642, a dielectric blocking region 652, amemory element 662, and a tunnel region (a portion of tunnel region676). As shown in FIG. 3A, tunnel region 676 can include a combinationof multiple tunnel dielectrics (e.g., different layers of dielectricmaterials) 671, 672, and 673. Tunnel dielectrics 671, 672, and 673 caninclude a region of dielectric oxide (e.g., silicon oxide), a region ofdielectric nitride (e.g., silicon nitride), and another region ofdielectric oxide (e.g., silicon oxide), respectively.

Each of voids 685 can be located (e.g., can occupy a location) betweentwo adjacent gates 683 and between two adjacent memory cell structures219. For example, FIG. 3A shows a void (one of voids 685) locatedbetween two gates 683 associated with memory cell structures 619 a ofmemory cells 612 and 613. Each of voids 685 can be separated from achannel portion (e.g., channel portion 680.3) of channel 680 by adielectric region (which is a portion of tunnel region 676).

As shown in FIG. 3A, gate 683 can include gate portions 681 a, 681 b,681 c, and 682. Gate portions 681 a, 681 b, 681 c can have the samematerial (e.g., conductive titanium nitride) that can be different fromthe material (e.g., tungsten) of gate portion 682. In an alternativestructure of memory device 300A, gate portions 681 a and 681 b can beomitted, such that gate portion 682 can occupy the location of gateportions 681 a and 681 b. In another alternative structure of memorydevice 300A, gate portions 681 a, 681 b, and 681 c can be omitted, suchthat gate portion 682 can occupy the location of gate portions 681 a,681 b, and 681 c.

The materials for sealing dielectric 687, gates 683, dielectric barrier642, dielectric blocking region 652, memory element 662, tunnel region676, channel 680, and portion 658 can be similar to or identical to thematerials for sealing dielectric 287, gates 283, dielectric barrier242M, dielectric blocking region 252M, memory element 262M, tunnelregion 276M, channel 280M, and portion 258 of FIG. 2E, respectively.

In FIG. 3B, the structure of the portion of memory device 300B can be avariation of the structure of the portion of memory device 300A of FIG.3A. Differences between memory devices 300A and 300B include (as shownin FIG. 3B) the exclusion (e.g., omission) of a portion of tunneldielectric 672 (e.g., silicon nitride) between two adjacent memory cellstructures 619 b in FIG. 3B. As shown in FIG. 3A, tunnel dielectric 673(e.g., silicon oxide) between two adjacent memory cell structures 619 ais unexposed (not exposed) to a corresponding void (one of voids 685 inFIG. 3A). In FIG. 3B, since a portion of tunnel dielectric 672 (e.g.,silicon nitride) between two adjacent memory cell structures 619 b isomitted (e.g., removed), a portion of tunnel dielectric 673 (e.g.,silicon oxide) between two adjacent memory cell structures 619 b isexposed to a corresponding void (one of voids 785). Each of voids 785 isan empty space that can contain air (an air-filled void (e.g., an airgap)) or gas (a gas-filled void). Memory device 300B can include sealingdielectric 787 (which is similar to sealing dielectric 687 of FIG. 3A)to seal off voids 785 in memory device 300B.

In FIG. 3C, the structure of the portion of memory device 300C can be avariation of the structure of the portion of memory device 300A of FIG.3A. Differences between memory devices 300C and 300A include (as shownin FIG. 3C) the structure of dielectric barrier 642′ in FIG. 3C. Asshown in FIG. 3C, dielectric barrier 642′ can be dielectric barrier 642(e.g., aluminum oxide or other high-k dielectric) of FIG. 3A where aportion (e.g., a top part and a bottom part) of dielectric barrier 642in FIG. 3A is removed from each of memory cell structures 619 c. In FIG.3C, since a portion of dielectric barrier 642 in each of memory cellstructures 619 c is omitted (e.g., removed) from each of memory cellstructures 619 c, dielectric blocking region 652 and memory element 662in each of memory cell structures 619 c are exposed to a correspondingvoid (one of voids 885) or exposed to two corresponding voids 885. Eachof voids 885 is an empty space that can contain air (an air-filled void(e.g., an air gap)) or gas (a gas-filled void).

As shown in FIG. 3C, each of gates 683 has thickness 683T extending inthe z-direction perpendicular to the x-direction (which is the directionchannel 680 to gates 683. FIG. 3C also shows that dielectric barrier642′ has length 642L (extending in the z-direction) less than thickness683T of the gates 683. As a comparison with FIG. 3A, the length ofdielectric barrier 642 can be at most equal to the thickness (e.g.,thickness 683T) of each of gates 683. Memory device 300C can includesealing dielectric 887 (which is similar to sealing dielectric 687 ofFIG. 3A) to seal off voids 885 in memory device 300C.

In FIG. 3D, the structure of the portion of memory device 300D can be avariation of the structure of the portion of memory device 300C of FIG.3C. Differences between memory devices 300D and 300C include (as shownin FIG. 3D) the exclusion (e.g., omission) of a portion of tunneldielectric 672 (e.g., silicon nitride) between two adjacent memory cellstructures 619 d in FIG. 3D. As shown in FIG. 3D, since a portion oftunnel dielectric 672 (e.g., silicon nitride) between two adjacentmemory cell structures 619 d is omitted (e.g., removed), a portion oftunnel dielectric 673 (e.g., silicon oxide) between two adjacent memorycell structures 619 d is exposed to a corresponding void (one of voids985). Each of voids 985 is an empty space that can contain air (anair-filled void (e.g., an air gap)) or gas (a gas-filled void). Memorydevice 300D can include sealing dielectric 987 (which is similar tosealing dielectric 687 of FIG. 3A) to seal off voids 985 in memorydevice 300D.

In FIG. 3E, the structure of the portion of memory device 300E can be avariation of the structure of the portion of memory device 300D of FIG.3D. Differences between memory devices 300E and 300D include (as shownin FIG. 3E) the inclusion (e.g., addition) of a region 684 in a channelportion (e.g., channel portion 680.3) of channel 680 that is exposed tovoids 1085. Each of voids 1085 is an empty space that can contain air(an air-filled void (e.g., an air gap)) or gas (a gas-filled void).Region 684 (e.g., doped region) can have an amount of dopants (e.g.,doping concentration) that is different from an amount of dopants (e.g.,doping concentration) in each of channel portions 680.1 and 680.2.Memory device 300E can include sealing dielectric 1087 (which is similarto sealing dielectric 687 of FIG. 3A) to seal off voids 1085 in memorydevice 300E.

As shown in FIG. 4A, memory device 400A can include elements similar toor identical to those of memory device 300A of FIG. 3A. Memory device400A can include memory cell structures 1119 a, a channel 1180, andvoids 1185. Each of voids 1185 is an empty space that can contain air(an air-filled void (e.g., an air gap)) or gas (a gas-filled void). Eachmemory cell structure 1119 a can be located between a respective gate(one of gates 683) and a channel portion of channel 1180. For example,memory cell 613 can include memory cell structure 1119 a located betweenone of gates 683 and channel portion 680.1, and memory cell 612 caninclude memory cell structure 1119 a located between one of gates 683and channel portion 680.2.

Each of voids 1185 can be located (e.g., can occupy a location) betweentwo adjacent gates 683 and between two adjacent memory cell structures1119 a. For example, FIG. 4A shows a void (one of voids 1185) locatedbetween two adjacent gates 683 associated with two corresponding memorycell structures 1119 a of memory cells 612 and 613. Each of voids 1185can be separated from channel portion (e.g., channel portion 680.3) ofchannel 1180 by a dielectric region (which is a portion of tunnel region1176).

Each of memory cell structures 1119 a can include a dielectric barrier(e.g., a dielectric region) 1142, a dielectric blocking region 652,material 1160′, a memory element 1162′, and a tunnel region (a portionof tunnel region 1176).

Channel 1180 can include a material similar to or identical to thematerial of channel 680 (FIG. 3A). Tunnel region 1176 can be a singletunnel dielectric (e.g., oxide). Alternatively, tunnel region 1176 caninclude a combination of multiple tunnel dielectrics (e.g., differentlayers of dielectric materials). Memory element 1162′ can bepolysilicon. Alternatively, memory element 1162′ can include othermaterials that can trap charge. Material 1160′ can include metal, ametallic compound, or a combination of metals and metallic compounds.Material 1160′ can surround the top, the bottom, and a side of memoryelement 1162′. In an alternative structure of memory device 400A,material 1160′ can be omitted from memory device 400A, such that memoryelement 1162′ can contact dielectric barrier 1142. As shown in FIG. 11G,dielectric barrier 1142 (e.g., high-k dielectric material) can surrounddielectric blocking region 652 (e.g., silicon oxide). Memory device 400Acan include sealing dielectric 1187 (which is similar to sealingdielectric 687 of FIG. 3A) to seal off voids 1185 in memory device 400A.

In FIG. 4B, the structure of the portion of memory device 400B can be avariation of the structure of the portion of memory device 400A of FIG.4A. Differences between memory devices 400B and 400A include (as shownin FIG. 4B) the structure of dielectric barrier 1142′ in FIG. 4B. Asshown In FIG. 4B, dielectric barrier 1142′ can be dielectric barrier 642(e.g., aluminum oxide or other high-k dielectric) of FIG. 3A where of aportion (e.g., a top part and a bottom part) of dielectric barrier 1142in FIG. 4A is removed from each of memory cell structures 1119 b. InFIG. 4B, since a portion of dielectric barrier 642 in each of memorycell structures 1119 b is omitted (e.g., removed) from each of memorycell structures 1119 b, dielectric blocking region 652 and memoryelement 1162′ in each of memory cell structures 1119 b are exposed to acorresponding void (one of voids 1285) or exposed to two correspondingvoids 1285. Each of voids 1285 is an empty space that can contain air(an air-filled void (e.g., an air gap)) or gas (a gas-filled void).Memory device 400B can include sealing dielectric 1287 (which is similarto sealing dielectric 687 of FIG. 3A) to seal off voids 1285 in memorydevice 400B.

In FIG. 5A, the structure of the portion of memory device 500A can be avariation of the structure of the portion of memory device 400A of FIG.4A. Differences between memory devices 500A and 400A include the absenceof voids 1185 in FIG. 5A. As shown in FIG. 5, memory device 500A caninclude dielectric material (e.g., silicon nitride) 624′ that occupiesthe same locations that voids 1185 occupy in memory device 400A (FIG.4A).

In FIG. 5B, the structure of the portion of memory device 500B can be avariation of the structure of the portion of memory device 400A of FIG.4A. Differences between memory devices 500B and 400A include the absenceof voids 1185 in FIG. 5B. As shown in FIG. 5B, memory device 500B caninclude dielectric material (e.g., silicon nitride) 622′ that occupiesthe same locations that voids 1185 occupy in memory device 400A (FIG.4A).

The voids in the memory devices described herein (e.g., the memorydevices shown in FIG. 2A through FIG. 5B) allow the distance (e.g.,vertical spacing) between tiers (e.g., vertical tier pitch in thez-direction) of memory cells of the memory device 600 to be relativelysmaller (e.g., about 30 nanometers or less). A smaller distance (e.g.,smaller vertical tier pitch (e.g., thinner tier pitch)) from one tier toanother may allow elements with relatively smaller dimensions (e.g.,smaller vertical sizes) to be formed in the memory devices describedherein. This in turn may allow the described memory devices to have ahigher memory storage density for a given device dimension (e.g.,vertical dimension) in comparison with some conventional memory devices.

Further, the voids in the memory devices described herein can have otherimprovements over conventional memory devices. For example, the voidsmay reduce coupling capacitance between the gates (e.g., between localword lines), such as gates 283 (FIG. 2E) or gates 683 (FIG. 3A throughFIG. 5B). In another example, as shown in FIG. 2D through FIG. 5B, thememory elements (e.g., memory element 262M, 662, or 1162′) of the memorycells (e.g., memory cells 210, 211, 212, and 213, or memory cells 610,611, 612, and 613) described herein are separated from each other (e.g.,the material that forms the memory elements is not a continuous layer(e.g., film) of material). This separation can prevent charge frommoving from one memory cell to another memory cell (an adjacent memorycell). This can improve the reliability of the information stored in thememory cells of the memory devices described herein. This can alsoreduce electrical resistance between memory cells, thereby furtherimproving the performance of the memory devices described herein.

FIG. 6A through FIG. 6O show cross-sectional views of elements duringprocesses of forming a memory device 600, according to some embodimentsof the invention. FIG. 6A shows memory device 600 after dielectricmaterials 622 and 624 are formed in respective levels 602 through 608 inthe z-direction. The z-direction (e.g., vertical direction) is adirection perpendicular to (e.g., outward from) substrate 699. Thez-direction is also perpendicular to the x-direction. As shown in FIG.6A, dielectric materials 622 and 624 can be formed over a portion 694 ofmemory device 600. In order not to obscure the embodiments describedherein, the processes of forming the structure of portion 694 of memorydevice 600 are omitted. However, one skilled in the art can recognizethat portion 694 can be formed to include a select transistor (e.g., asource select transistor) or multiple select transistors (e.g., multipleseries-connected source select transistors) of a memory cell string. Theselect transistor (or select transistors) in portion 694 can be similarto select transistor 262 of FIG. 2C.

As shown in FIG. 6A, dielectric materials 622 and 624 can be formed overa conductive region 692, which can be formed over substrate 699.Conductive region 692 and substrate 699 can be similar to or identicalto conductive region 292, and substrate 299, respectively, of FIG. 2C.

In FIG. 6A, forming dielectric materials 622 and 624 can includedepositing alternating dielectric materials (e.g., alternating layers ofdielectric materials 622 and layers of dielectric materials 624) inrespective levels 602 through 608. Dielectric materials 622 can includean oxide material (e.g., silicon dioxide SiO₂). Dielectric materials 624can include a nitride material (e.g., silicon nitrite SiN₄). FIG. 6Ashows seven layers of dielectric materials 622 and 624 as an example.The number of layers of dielectric materials 622 and 624 can bedifferent from seven, depending on the number of tiers (e.g., verticaltiers in the z-direction) of memory cells to be included in memorydevice 600.

FIG. 6B shows locations (in dashed lines) in dielectric materials 622and 624 where an opening (e.g., hole) 632 will be formed in a subsequentprocess.

FIG. 6C shows memory device 600 after opening 632 is formed. Formingopening 632 can include removing parts of dielectric materials 622 and624 (at the location of opening 632) leaving a remaining part ofdielectric materials 622 and 624, which are dielectric materials 622′and 624′, respectively.

FIG. 6D shows memory device 600 after recesses 624R are formed. Formingrecesses 624R can include removing a portion of dielectric materials624′ (at the locations of recesses 624R) and leaving a remaining portionof dielectric materials 624″ as shown in FIG. 6D. An etch process can beused to remove the portion of dielectric materials 624′ (FIG. 6C) toform recesses 624R (FIG. 6D). The etch process can include an atomiclayer etching (ALE) process.

FIG. 6E shows memory device 600 after a barrier material (or materials)640 is formed. A portion of barrier material 640 can be part of adielectric barrier for a memory cell of memory device 600 (as describedbelow in subsequent processes of forming memory device 600). As shown inFIG. 6E, barrier material 640 can be formed such that barrier material640 is conformal to a wall of each of recesses 624R and walls of otherportions of opening 632 (e.g., vertical walls of dielectric materials622′ in opening 632).

Forming barrier material 640 can include depositing one or more ofhigh-k dielectric materials through opening 632 The high-k dielectricmaterials can include the materials for dielectric barrier 242Mdescribed above with reference to FIG. 2E. Thus, as an example, formingbarrier material 640 can include depositing (through opening 632) one ofaluminum oxide, hafnium oxide, and zirconium oxide. In another example,forming barrier material 640 can include depositing a mixture of hafniumoxide with at least one of aluminum oxide, silicon oxide, titaniumoxide, gadolinium oxide, niobium oxide, and tantalum oxide. In anotherexample, forming barrier material 640 can include depositing (throughopening 632) a mixture of zirconium oxide with at least one of aluminumoxide, silicon oxide, titanium oxide, gadolinium oxide, niobium oxide,and tantalum oxide. In another example, forming barrier material 640 caninclude depositing a mixture of hafnium oxide and zirconium oxide withat least one of aluminum oxide, silicon oxide, titanium oxide,gadolinium oxide, niobium oxide, and tantalum oxide. Forming barriermaterial 640 can include depositing other high-k dielectrics.

The deposition of barrier material 640 (e.g., deposition of high-kdielectric or dielectrics through opening 632) can be performed usingone or more of a number of deposition processes. For example, thedeposition can be implemented using chemical vapor deposition (CVD),atomic layer deposition (ALD), or another process suitable for forming a3D memory device, such as memory device 600. An ALD process allowsformation of a region as a nanolaminate of a number of differentcompounds in each sub-region of the region, such that the formed regionhas a total thickness in the nanometer range. The term “nanolaminate”means a composite film of ultra thin layers of two or more materials ina layered stack. Typically, each layer in a nanolaminate has a thicknessof an order of magnitude in the nanometer range. Further, eachindividual material layer of the nanolaminate may have a thickness aslow as a monolayer of the material or as high as multiple nanometers(e.g., 5 nanometers).

In FIG. 6E, barrier material 640 can be formed to have a thickness inthe range from about 15 angstroms to about 50 angstroms. The thicknessof barrier material 640 is measured from the wall of each of recesses624R and from the wall of the other portions of opening 632 (e.g., fromthe vertical walls of dielectric materials 622′ in opening 632).

FIG. 6F shows memory device 600 after a blocking material (or materials)650 is formed in each of recesses 624R through opening 632. A portion ofblocking material 650 can be part of a dielectric blocking region for amemory cell of memory device 600 (as described below in subsequentprocesses of forming memory device 600). In FIG. 6F, blocking material650 can include silicon oxide or other dielectric materials. Blockingmaterial 650 can be selected to be different from barrier material 640.Blocking material 650 can be formed by depositing (e.g., using an ALDprocess or other processes) a dielectric material (e.g., silicon oxide)on barrier material 640 (including in barrier material 640 recesses624R). Then, another process (e.g., an etch process) can be performed toremove (e.g., cut) a portion of the dielectric material (e.g., siliconoxide). The remaining portion of the dielectric material (e.g., siliconoxide) is blocking material 650 (in FIG. 6F) located in each of recesses624R.

FIG. 6G shows memory device 600 after a dielectric blocking region 652is formed in each of recesses 624R. Dielectric blocking region 652 canbe formed by removing a portion of blocking material 650 (FIG. 6F) ineach of recesses 624R and leaving a remaining portion of blockingmaterial 650 (which is dielectric blocking region 652) in each ofrecesses 624R. As shown in FIG. 6G, dielectric blocking region 652 ineach of recesses 624R can have a thickness (e.g., horizontal thicknessin the x-direction) such that the entire dielectric blocking region 652can be located in a respective recess among recesses 624R. This meansthat no portion of dielectric blocking region 652 at a particular recess(among recesses 624R) is outside that particular recess.

FIG. 6H shows memory device 600 after a memory element 662 is formed ineach of recesses 624R. The material used to form memory element 662 caninclude a dielectric nitride (e.g., silicon nitride) or other materialscapable of storing (e.g., trapping) charge that can represent the valueof information stored in memory element 662. Memory element 662 can beformed by depositing (e.g., using an ALD process or by other processes)a dielectric material (e.g., silicon nitride or other materials) ondielectric blocking region 652 in recesses 624R and on barrier material640. Then, another process (e.g., an etch process) can be performed toremove (e.g., cut) a portion of the dielectric material (e.g., siliconnitride). The remaining portion of the dielectric material is memoryelement 662 located in each of recesses 624R.

Additional processes can be performed to memory element 662. Forexample, an oxidation process can be performed to oxidize a portion(e.g., surface) 662 a of memory element 662. In another example, aportion (e.g., portion 662 b) of memory element 662 can be removed(e.g., cut), such that only a portion 662 c of memory element 662remains in each of recesses 624R.

FIG. 6I shows memory device 600 after a portion of barrier material 640(FIG. 6H) is removed to form a dielectric barrier 642 in each ofrecesses 624R. An ALE process can be used to remove (e.g., pattern)barrier material 640 of FIG. 6H in order to form dielectric barrier 642of FIG. 6I. An ALE process is similar to an ALD process except that ALDis a deposition process and an ALE process is a removal process. An ALEprocess is a material removal technique based on sequential,self-limiting surface reactions. An ALE process provides the capabilityto remove films with atomic layer control, allowing nanofabrication of awide range of electronic devices. ALE removal of Al₂O₃ has been reportedusing sequential, self limiting thermal reactions with tin(II)acetylacetonate (Sn(acac)₂) and HF as reactants in the cycles. Use ofSn(acac)₂ and HF to etch Al₂O₃ providing linear removal of Al₂O₃ attemperatures from 150° C. to 250° C. at etch rates of angstroms percycle, dependent on the processing temperature, was reported. ALE ofHfO₂ has also been reported using Sn(acac)₂ and HF as the reactants insequential, self-limiting thermal reactions, where linear removal of theHfO₂ by the ALE process was achieved. Other materials, which may beetched by ALE, include other metal oxides, metal nitrides, metalphosphides, metal sulfides, and metal arsenides.

FIG. 6J shows memory device 600 after a tunnel region 676 is formed.Tunnel region 676 can include a combination of multiple tunneldielectrics (e.g., different layers of dielectric materials) 671, 672,and 673. Tunnel dielectrics 671, 672, and 673 can include a region ofdielectric oxide (e.g., silicon oxide), a region of dielectric nitride(e.g., silicon nitride), and another region of dielectric oxide (e.g.,silicon oxide), respectively. In an alternative structure of memorydevice 600, one or two of tunnel dielectrics 671, 672, and 673 can beomitted from tunnel region 676. For example, tunnel dielectric 671 or672, or both, can be omitted. In another alternative structure of memorydevice 600, tunnel region 676 may have four or more than four tunneldielectrics (e.g., four or more different layers of dielectricmaterials). Dielectric nitride (e.g., silicon nitride) and dielectricoxide (e.g., silicon oxide) are used herein as an example for thematerial (or materials) for tunnel region 676. However, other dielectricmaterials can be used for tunnel region 676.

In FIG. 6J, forming tunnel dielectric 671 can include performingoxidization process (e.g., in situ steam generation (ISSG)) to formtunnel dielectric 671 on a portion of the material (e.g., dielectricnitride) that is included in memory element 662. Thus, tunnel dielectric671 (e.g., silicon oxide) can be a portion of memory element 662 (e.g.,silicon nitride) that has been oxidized by an oxidization process.Tunnel dielectric 672 can be formed after tunnel dielectric 671 isformed. Forming tunnel dielectric 672 can include depositing adielectric material (e.g., silicon nitride or other dielectricmaterials) on tunnel dielectric 671 (through opening 632) and on otherparts of opening 632 (as shown in FIG. 6J). Tunnel dielectric 673 can beformed after tunnel dielectric 672 is formed. Forming tunnel dielectric673 can include performing an oxidization process (e.g., in situ steamgeneration (ISSG)) to form tunnel dielectric 673 on tunnel dielectric672. Thus, tunnel dielectric 673 (e.g., silicon oxide) can be a portionof tunnel dielectric 672 (e.g., silicon nitride) that has been oxidizedby an oxidization process. As shown in FIG. 6J, dielectric blockingregion 652 and memory element 662 are already formed in each of recesses624R. This can improve margin for a subsequent punch etch process (e.g.,a process to form a conductive path (e.g., a channel 680 in FIG. 6K)connecting to conductive region 692).

FIG. 6K shows memory device 600 after a channel 680 is formed. Channel680 can be similar to (or identical to) a portion (e.g., portion betweenlevels 202 through 208) of channel 280M of FIG. 2D. Channel 680 in FIG.6K can be a semiconductor material. Example materials for channel 680include polysilicon (e.g., undoped to doped polysilicon). Channel 680can be polysilicon of n-type or polysilicon of p-type).

FIG. 6L shows memory device 600 after dielectric materials 624″ (FIG.6K) are removed from locations 624G. As shown in FIG. 6L, dielectricbarrier 642 in each of recesses 624R (labeled in FIG. 6D) is exposed ata respective location 624G. As described below, gates (e.g., controlgates that can be part of word lines) of memory device 600 can be formedin locations 624G where dielectric materials 624″ were removed.

FIG. 6M shows memory device 600 after gates 683 are formed in locations624G. Each of gates 683 contacts a respective dielectric barrier 642.Each of gates 683 can be metal gates. Each of gates 683 can include gateportions 681 a, 681 b, 681 c, and 682. Gate portions 681 a, 681 b, 681 ccan have the same conductive material (e.g., conductive titaniumnitride) that can be different from the conductive material (e.g.,tungsten) of gate portion 682. In an alternative structure of gates 683,gate portions 681 a and 681 b can be omitted, such that gate portion 682can occupy the location of gate portions 681 a and 681 b. In anotheralternative structure of gates 683, gate portions 681 a, 681 b, and 681c can be omitted, such that gate portion 682 can occupy the location ofgate portions 681 a, 681 b, and 681 c. In FIG. 6M, forming gates 683 caninclude depositing (e.g., by using an ALD process or by other processes)a conductive material (e.g., conductive titanium nitride) in part oflocations 624G (on the walls of locations 624G) to form either only gateportions 681 c or all of gate portions 681 a, 681 b, and 681 c, and thendepositing another conductive material (e.g., tungsten) in the rest oflocations 624G to form gate portions 682.

FIG. 6N shows memory device 600 after dielectric materials 622′ (FIG.6M) are removed from locations 622A. As shown in FIG. 6N, sincedielectric materials 622′ (e.g., silicon oxide) are removed, no siliconoxide is directly located between memory elements 662 at location 622A.As described below, voids of memory device 600 can be formed inlocations 622A where dielectric materials 622′ were removed.

FIG. 6O shows memory device 600 after voids 685 and sealing dielectric687 of memory device 600 are formed. As shown in FIG. 6O, voids 685 canbe located at locations 622A where dielectric materials 622′ wereremoved. Sealing dielectric 687 may be formed by a sealing process thatcan include plasma-enhanced chemical vapor deposition (PECVD) process orother depleting processes. Voids 685 can be formed by intentionallyleaving empty spaces at locations 622A (FIG. 6N) after dielectricmaterials 622′ (FIG. 6M) are removed from locations 622A (FIG. 6N). Eachof voids 685 (FIG. 6O) contains no conductive material (e.g., metal,conductive polysilicon, or other conductive materials) or no dielectricmaterial (e.g., oxide, nitride, or other dielectric materials). Each ofvoids 685 may contain air (an air-filled void) or gas (a gas-filledvoid). Voids 685 (FIG. 6O) remain in memory device 600 after memorydevice 600 is completed. FIG. 6O also shows a portion 658 of memorydevice 600. The process of forming memory device 600 can include forming(e.g., by using a deposition process) a dielectric material (e.g.,silicon oxide) or a conductive material in portion 658. Alternatively,the process of forming memory device 600 may leave portion 658 empty(e.g., not fill portion 658 with a material).

After the structure of memory device 600 shown in FIG. 6O is formed,additional processes can be used to complete memory device 600. Aftercompletion, memory device 600 can include elements similar to a memorydevice 100 (FIG. 1) and memory device 200 (FIG. 2A through FIG. 2E).

As shown in FIG. 6O, memory device 600 includes elements that aresimilar to or identical to memory device 300A (FIG. 3A). Thus, theprocesses described above with reference to FIG. 6A through FIG. 6O canalso be used to form memory device 300A.

FIG. 7A and FIG. 7B show cross-sectional views of elements duringprocesses of forming a memory device 700, according to some embodimentsdescribed herein. Memory device 700 can be a variation of memory device600. Thus, some of the processes (described above with reference to FIG.6A through FIG. 6O) used to form memory device 600 can be used to formmemory device 700 of FIG. 7A and FIG. 7B. For example, the elements ofFIG. 7A are the same as the elements of FIG. 6N, except for locations672A in FIG. 7A. As shown in FIG. 7A, a portion of tunnel dielectric 672(e.g., silicon nitride) has been removed from locations 672A. Removingthe portion of tunnel dielectric 672 from locations 672A can includeetching tunnel dielectric 672 at locations 672A selective to otherelements next to locations 672A (e.g., selective to gate 683, dielectricbarrier 642, and tunnel dielectric 673).

FIG. 7B shows memory device 700 after voids 785 and sealing dielectric787 are formed. Sealing dielectric 787 may be formed by a processsimilar to that of the process used to form sealing dielectric 687 (FIG.6O) of memory device 600.

As shown in FIG. 7B, voids 785 can occupy (e.g., can be located at)locations 622A and 672A (labeled in FIG. 7A). Voids 785 can be formed byintentionally leaving empty spaces at locations 622A and 672A afterdielectric materials 622′ (e.g., silicon oxide) and a portion of tunneldielectric 672 (e.g., silicon nitride) are removed from respectivelocations 622A and 672A. Each of voids 785 (FIG. 7B) contains noconductive material (e.g., metal, conductive polysilicon, or otherconductive materials) or no dielectric material (e.g., oxide, nitride,or other dielectric materials). Each of voids 785 may contain air (anair-filled void) or gas (a gas-filled void). Voids 785 (FIG. 7B) remainin memory device 700 after memory device 700 is completed.

After the structure of memory device 700 shown in FIG. 7B is formed,additional processes can be used to complete memory device 700. Aftercompletion, memory device 700 can include elements similar to memorydevice 100 (FIG. 1) and memory device 200 (FIG. 2A through FIG. 2E).

As shown in FIG. 7B, memory device 700 includes elements that aresimilar to or identical to memory device 300B (FIG. 3B). Thus, theprocesses used to form memory device 700 can also be used to form memorydevice 300B.

FIG. 8A and FIG. 8B show cross-sectional views of elements duringprocesses of forming memory device 800, according to some embodimentsdescribed herein. Memory device 800 can be a variation of memory device600 (FIG. 6O). Thus, some of the processes (described above withreference to FIG. 6A through FIG. 6O) used to form memory device 600 canbe used to form memory device 800 of FIG. 8A and FIG. 8B. For example,the elements of FIG. 8A are the same as the elements of FIG. 6N, exceptfor locations 642A and 642B in FIG. 8A. In FIG. 8A, dielectric barrier642′ (e.g., high-k dielectric material) is a remaining (unremoved)portion of dielectric barrier 642 (e.g., high-k dielectric material) ofFIG. 6N after a portion of dielectric barrier 642 has been removed fromlocations 642A and 642B. Removing a portion of dielectric barrier 642(FIG. 6N) from locations 642A and 642B can include etching (e.g., usingan ALE process) a portion of dielectric barrier 642 (FIG. 6N) atlocations 642A and 642B selective to other elements next to locations642A and 642B (e.g., gate 683, dielectric blocking region 652, memoryelement 662, and tunnel dielectric 672).

FIG. 8B shows memory device 800 after voids 885 and sealing dielectric887 are formed. Sealing dielectric 887 may be formed by a processsimilar to that of the process used to form sealing dielectric 687 (FIG.6O) of memory device 600.

As shown in FIG. 8B, voids 885 can occupy (e.g., can be located at)locations 622A, 642A, and 642B (labeled in FIG. 8A). Voids 885 can beformed by intentionally leaving empty spaces at locations 622A, 642A,and 642B after dielectric materials 622′ (e.g., silicon oxide) and aportion of dielectric barrier 642 (e.g., high-k dielectric material) areremoved from respective locations 622A, 642A, and 642B. Each of voids885 (FIG. 8B) contains no conductive material (e.g., metal, conductivepolysilicon, or other conductive materials) or no dielectric material(e.g., oxide, nitride, or other dielectric materials). Each of voids 885may contain air (an air-filled void) or gas (a gas-filled void). Voids885 (FIG. 8B) remain in memory device 800 after memory device 800 iscompleted.

After the structure of memory device 800 shown in FIG. 8B is formed,additional processes can be used to complete memory device 800. Aftercompletion, memory device 800 can include elements similar to memorydevice 100 (FIG. 1) and memory device 200 (FIG. 2A through FIG. 2E).

As shown in FIG. 8B, memory device 800 includes elements that aresimilar to or identical to memory device 300C (FIG. 3C). Thus, theprocesses used to form memory device 800 can also be used to form memorydevice 300C.

FIG. 9A and FIG. 9B show cross-sectional views of elements duringprocesses of forming memory device 900, according to some embodimentsdescribed herein. Memory device 900 can be a variation of memory device800 (FIG. 8A and FIG. 8B). Thus, some of the processes used to formmemory device 800 can be used to form memory device 900 of FIG. 9A andFIG. 9B. For example, the elements of FIG. 9A are the same as theelements of FIG. 8A, except for locations 672A in FIG. 9A. As shown inFIG. 9A, a portion of tunnel dielectric 672 has been removed fromlocations 672A. Removing a portion of tunnel dielectric 672 (e.g.,silicon nitride), from locations 672A can include etching a portion oftunnel dielectric 672 at locations 672A selective to other elements nextto locations 672A (e.g., gate 683, dielectric barrier 642′, dielectricblocking region 652, memory element 662, and tunnel dielectric 673).Removing the portion of tunnel dielectric 672 from locations 672A can beperformed before or after the portion of dielectric barrier 642 isremoved from locations 642A and 642B.

FIG. 9B shows memory device 900 after voids 985 and sealing dielectric987 are formed. Sealing dielectric 987 may be formed by a processsimilar to that of the process used to form sealing dielectric 887 (FIG.8B) of memory device 800.

As shown in FIG. 9B, voids 985 can occupy (e.g., can be located at)locations 622A, 642A, 642B, and 672A (labeled in FIG. 9A). Voids 985 canbe formed by intentionally leaving empty spaces at locations 622A, 642A,642B, and 672A after dielectric materials 622′ (e.g., silicon oxide), aportion of dielectric barrier 642 (e.g., high-k dielectric material),and a portion of tunnel dielectric 672 (e.g., silicon nitride) areremoved from respective locations 622A, 642A, 642B, and 672A. Each ofvoids 985 (FIG. 9B) contains no conductive material (e.g., metal,conductive polysilicon, or other conductive materials) or no dielectricmaterial (e.g., oxide, nitride, or other dielectric materials). Each ofvoids 985 may contain air (an air-filled void) or gas (a gas-filledvoid). Voids 985 (FIG. 9B) remain in memory device 900 after memorydevice 900 is completed.

After the structure of memory device 900 shown in FIG. 9B is formed,additional processes can be used to complete memory device 900. Aftercompletion, memory device 900 can include elements similar to memorydevice 100 (FIG. 1) and memory device 200 (FIG. 2A through FIG. 2E).

As shown in FIG. 9B, memory device 900 includes elements that aresimilar to or identical to memory device 300D (FIG. 3D). Thus, theprocesses used to form memory device 900 can also be used to form memorydevice 300D.

FIG. 10A, FIG. 10B, and FIG. 10C show cross-sectional views of elementsduring processes of forming memory device 1000, according to someembodiments described herein. Memory device 1000 can be a variation ofmemory device 900 (FIG. 9A and FIG. 9B). Thus, some of the processesused to form memory device 900 can be used to form memory device 1000 ofFIG. 10A, FIG. 10B, and FIG. 10C. For example, the elements of FIG. 10Aare the same as the elements of FIG. 9A, except for locations 673A inFIG. 10A. As shown in FIG. 10A, a portion of tunnel dielectric 673(e.g., silicon oxide) has been removed from locations 673A. Removing aportion of tunnel dielectric 673 from locations 673A can include etchinga portion of tunnel dielectric 673 at locations 673A selective to otherelements next to locations 673A (e.g., gate 683, dielectric barrier642′, dielectric blocking region 652, memory element 662, tunneldielectric 672, and channel 680). Removing the portion of tunneldielectric 673 from locations 673A can be performed after the portion oftunnel dielectric 672 is removed from locations 672A.

FIG. 10B, shows memory device 1000 after a region 684 is formed in achannel portion of channel 680 (the channel portion that is exposed atlocation 673A. Forming region 684 can include introducing dopants(impurities) into the channel portion of channel 680 at location 673A.Region 684 (e.g., doped region) can be formed such that it can have anamount of dopants (e.g., doping concentration) that is different from anamount of dopants (e.g., doping concentration) in another portion (e.g.,in each of channel portions 680.1 and 680.2 (labeled in FIG. 3E)) ofchannel 680.

FIG. 10C shows memory device 1000 after voids 1085 and sealingdielectric 1087 are formed. Sealing dielectric 1087 may be formed by aprocess similar to that of the process used to form sealing dielectric887 (FIG. 8B) of memory device 800.

As shown in FIG. 10C, voids 1085 can occupy (e.g., can be located at)locations 622A, 642A, 642B, 672A, and 673A (labeled in FIG. 10A). Voids1085 can be formed by intentionally leaving empty spaces at locations622A, 642A, 642B, 672A, and 673A after dielectric materials 622′ (e.g.,silicon oxide), a portion of dielectric barrier 642 (e.g., high-kdielectric material), a portion of tunnel dielectric 672 (e.g., siliconnitride), and a portion of tunnel dielectric 673 (e.g., silicon oxide)are removed from respective locations 622A, 642A, 642B, 672A, and 673A.Each of voids 1085 (FIG. 10B) contains no conductive material (e.g.,metal, conductive polysilicon, or other conductive materials) or nodielectric material (e.g., oxide, nitride, or other dielectricmaterials). Each of voids 1085 may contain air (an air-filled void) orgas (a gas-filled void). Voids 1085 (FIG. 10B) remain in memory device1000 after memory device 1000 is completed.

After the structure of memory device 1000 shown in FIG. 10B is formed,additional processes can be used to complete memory device 1000. Aftercompletion, memory device 1000 can include elements similar to memorydevice 100 (FIG. 1) and memory device 200 (FIG. 2A through FIG. 2E).

As shown in FIG. 10B, memory device 1000 includes elements that aresimilar to or identical to memory device 300E (FIG. 3D). Thus, theprocesses used to form memory device 1000 can also be used to formmemory device 300E.

FIG. 11A through FIG. 11P show cross-sectional views of elements duringprocesses of forming a memory device 1100, according to some embodimentsdescribed herein. The processes and elements (e.g., materials) forforming memory device 1100 are similar to or identical to processes andelements used to form memory devices 600, 700, 800, 900, and 1100described above with reference to FIG. 6A through FIG. 6O and FIG. 7Athrough FIG. 10C. Thus, for simplicity, details of similar or identicalprocesses are not repeated. Also for simplicity, details of similar (oridentical) elements (e.g., elements having the same reference labels)between memory device 1100 and memory devices 600, 700, 800, 900, and1100 (FIG. 6A through FIG. 10C) are not repeated.

FIG. 11A shows memory device 1100 after an opening (e.g., hole) 1132 isformed in dielectric materials 622′ and 624′ and over portion 694,conductive region (e.g., source region) 692, and substrate 699. Asdescribed above, dielectric materials 622′ can include an oxide material(e.g., silicon dioxide SiO₂), and dielectric materials 624′ can includea nitride material (e.g., silicon nitrite SiN₄).

FIG. 11B shows memory device 1100 after recesses 622R are formed inrespective dielectric materials 622′. Forming recesses 622R can includeremoving a portion of dielectric materials 622′ (at the locations ofrecesses 622R) and leaving a remaining portion of dielectric materials622″ as shown in FIG. 11B. An etch process can be used to remove theportion of dielectric materials 622′ (FIG. 11A) to form recesses 622R(FIG. 11B). The etch process can include an atomic layer etching (ALE)process. For comparison purposes, recesses 622R in FIG. 11B are formedby removing a portion of dielectric materials 622′ (e.g., silicondioxide SiO₂), whereas recesses 624R in FIG. 6D are formed by removing aportion of dielectric materials 624′ (silicon nitrite SiN₄).

FIG. 11C shows memory device 1100 after a barrier material (ormaterials) 1140 is formed. A portion of barrier material 1140 can bepart of a dielectric barrier for a memory cell of memory device 1100 (asdescribed below in subsequent processes of forming memory device 1100).Similar or identical processes of forming barrier material 640 (FIG. 6E)can be used to form barrier material 1140 of FIG. 11C. Barrier material1140 can include any of the material (or materials) for barrier material640 (e.g., high-k dielectric material) described above with reference toFIG. 6E.

FIG. 11D shows memory device 1100 after a blocking material (ormaterials) 650 (e.g., silicon oxide) is formed in each of recesses 622R.Blocking material 650 can be formed by depositing a dielectric material(e.g., silicon oxide) on barrier material 1140. Then, another process(e.g., an etch process) can be performed to remove (e.g., cut) a portionof the dielectric material (e.g., silicon oxide). The remaining portionof the dielectric material (e.g., silicon oxide) is blocking material650 in FIG. 11D.

FIG. 11E shows memory device 600 after a dielectric blocking region 652is formed in each of recesses 622R. Dielectric blocking region 652 ineach of recesses 624R can be formed by removing a portion of blockingmaterial 650 (FIG. 11D) in each of recesses 622R.

FIG. 11F shows memory device 1100 after a barrier material 1140′ isformed. Barrier material 1140′ can include the same material as barriermaterial 1140. Alternatively, barrier material 1140′ can include adielectric material (e.g., a high-k dielectric material) different fromthe material of barrier material 1140.

FIG. 11G shows memory device 1100 after dielectric barrier 1142 isformed. Forming dielectric barrier 1142 (e.g., high-k dielectricmaterial) can include removing a portion of barrier material 1140 (FIG.11F) and a portion of barrier material 1140′ (FIG. 11F) leaving aportion of material 1140 and a portion of material 1140′ unremoved. Theunremoved portions of barrier materials 1140 and 1140′ (as shown in FIG.11G) form dielectric barrier 1142. An ALE process can be used to removea portion of barrier material 1140 (FIG. 11F) and a portion of material1140′ (FIG. 11F). As shown in FIG. 11G, dielectric barrier 1142 (e.g.,high-k dielectric material) can surround dielectric blocking region 652(e.g., silicon oxide).

FIG. 11H shows memory device 1100 after a material 1160 and a memorymaterial 1162 are formed. Material 1160 can be formed (e.g., by usingALD, CVD, or other processes) before memory material 1162 is formed.Material 1162 can include metal, a metallic compound, or a combinationof metals and metallic compounds. Memory material 1162 can bepolysilicon or other materials capable of trapping charge to representthe value of information stored in a memory cell that includes memorymaterial 1162. Memory material 1162 can be used to form a memory elementof a memory cell of memory device 1100 (as described below in subsequentprocesses of forming memory device 1100). In an alternative structure ofmemory device 1100, the process of forming material 1160 can be omitted.Thus, material 1160 may or may not be present in memory device 1100.

FIG. 11I shows memory device 1100 after a portion of memory material1162 is removed to form a memory element 1162′ in each of recesses 622R.Removing the portion of memory material 1162 to form memory element1162′ can include using an etch process. Alternatively, an oxidizationprocess can be used to oxidize a portion of memory material 1162 andleave a portion of memory material 1162 unoxidized. The unoxidizedportion of memory material 1162 becomes memory element 1162′. Theoxidized portion of memory material 1162 can be removed. Thus, either anetch process or an oxidization process can be used to form thestructures of memory element 1162′ and material 1160 shown in FIG. 11I.

FIG. 11J shows memory device 1100 after a portion of material 1160 isremoved (e.g., by using an etch process), leaving portion of material1160 unremoved, which is material 1160′. As shown in FIG. 11J, material1160′ can surround the top, the bottom, and a side of memory element1162′.

FIG. 11K shows memory device 1100 after a tunnel region 1176 is formed.Tunnel region 1176 can include a dielectric material (e.g., siliconoxide). FIG. 11K shows tunnel region 1176 including a single tunneldielectric (e.g., a layer of silicon oxide) as an example.Alternatively, tunnel region 1176 can include more than one tunneldielectrics (e.g., more than one different layers of dielectricmaterials). For example, tunnel region 1176 can include three differenttunnel dielectrics (e.g., a dielectric nitride region (e.g., a layer ofsilicon nitride) sandwiched between two dielectric oxide regions (e.g.,two layers of silicon oxide)).

FIG. 11L shows memory device 600 after a channel 1180 is formed. Channel1180 can be similar to (or identical to) a portion (e.g., portionbetween levels 202 through 208) of channel 280M of FIG. 2D. Channel 1180in FIG. 11L includes polysilicon (e.g., undoped to doped polysilicon).

FIG. 11M shows memory device 1100 after dielectric materials 622″ (FIG.11L) is removed from locations 622G. As described below, gates of memorydevice 1100 can be formed in locations 622G where dielectric materials622″ were removed.

FIG. 11N shows memory device 1100 after gates 683 are formed in each oflocations 622G. Gates 683 can be formed by similar or identicalprocesses used to form gate 683 (FIG. 6M). As described above, one ormore of gate portions 681 a, 681 b, and 681 c can be omitted from gates683.

FIG. 11O shows memory device 1100 after dielectric materials 624′ (FIG.6M) are removed from locations 624A. As described below, voids of memorydevice 1100 can be formed in locations 624A where dielectric materials624′ were removed.

FIG. 11P shows memory device 1100 after voids 1185 and sealingdielectric 1187 are formed. Sealing dielectric 1187 may be formed by aprocess similar to that of the process used to form sealing dielectric687 (FIG. 6O) of memory device 600. As shown in FIG. 11P, voids 1185 canoccupy (e.g., can be located at) locations 624A. Voids 1185 can beformed by intentionally leaving empty spaces at locations 624A (FIG.11O) after dielectric materials 624′ (FIG. 11N) are removed fromrespective locations 624A (FIG. 11O). Each of voids 1185 (FIG. 11P)contains no conductive material (e.g., metal, conductive polysilicon, orother conductive materials) or no dielectric material (e.g., oxide,nitride, or other dielectric materials). Each of voids 1185 may containair (an air-filled void) or gas (a gas-filled void). Voids 1185 (FIG.11P) remain in memory device 1100 after memory device 1100 is completed.FIG. 11P also shows portion 658 of memory device 1100. The process offorming memory device 1100 can include forming (e.g., by using adeposition process) a dielectric material (e.g., silicon oxide) or aconductive material in portion 658. Alternatively, the process offorming memory device 600 may leave portion 658 empty (e.g., not fillportion 658 with a material).

After the structure of memory device 1100 shown in FIG. 11P is formed,additional processes can be used to complete memory device 1100. Aftercompletion, memory device 1100 can include elements similar to memorydevice 100 (FIG. 1) and memory device 200 (FIG. 2A through FIG. 2E).

FIG. 12A and FIG. 12B show cross-sectional views of elements duringprocesses of forming memory device 1200, according to some embodimentsdescribed herein. Memory device 1200 can be a variation of memory device1100. Thus, some of the processes (described above with reference toFIG. 11A through FIG. 11P) used to form memory device 1100 can be usedto form memory device 1200 of FIG. 12A and FIG. 12B. For example, theelements of FIG. 12A are the same as the elements of FIG. 11O, exceptfor locations 1142A and 1142B in FIG. 12A. In FIG. 12A, dielectricbarrier 1142′ (e.g., high-k dielectric material) is a remaining(unremoved) portion of dielectric barrier 1142 (e.g., high-k dielectricmaterial) of FIG. 11O after a portion of dielectric barrier 1142 hasbeen removed from locations 1142A and 1142B. Removing a portion ofdielectric barrier 1142 from locations 1142A and 1142B can includeetching (e.g., using an ALE process) a portion of dielectric barrier1142 at locations 1142A and 1142B selective to other elements next tolocations 1142A and 1142B (e.g., gate 683, dielectric blocking region652, material 1160′, memory element 1162′, and tunnel region 1176).

FIG. 12B shows memory device 1100 after voids 1285 and sealingdielectric 1287 are formed. Sealing dielectric 1287 may be formed by aprocess similar to that of the process used to form sealing dielectric1187 (FIG. 11P) of memory device 1100.

As shown in FIG. 12B, voids 1285 can occupy (e.g., can be located at)locations 624A, 1142A, and 1142B (labeled in FIG. 12A). Voids 1285 canbe formed by intentionally leaving empty spaces at locations 624A,1142A, and 1142B after dielectric materials 624′ (e.g., siliconnitride), and a portion of dielectric barrier 1142 (e.g., high-kdielectric material) are removed from respective locations 624A, 1142A,and 1142B. Each of voids 1285 (FIG. 12B) contains no conductive material(e.g., metal, conductive polysilicon, or other conductive materials) orno dielectric material (e.g., oxide, nitride, or other dielectricmaterials). Each of voids 1285 may contain air (an air-filled void) orgas (a gas-filled void). Voids 1285 (FIG. 12B) remain in memory device1200 after memory device 1200 is completed.

After the structure of memory device 1200 shown in FIG. 12B is formed,additional processes can be used to complete memory device 1200. Aftercompletion, memory device 1200 can include elements similar to memorydevice 100 (FIG. 1) and memory device 200 (FIG. 2A through FIG. 2E).

As shown in FIG. 12B, memory device 1200 includes elements that aresimilar to or identical to memory device 400B (FIG. 4B). Thus, theprocesses used to form memory device 1200 can also be used to formmemory device 400B.

FIG. 13 shows cross-sectional views of elements during processes offorming memory device 1300, according to some embodiments describedherein. Memory device 1300 can be a variation of memory device 1100 ofFIG. 11P. Thus, some of the processes (e.g., the process described abovewith reference to FIG. 11A through FIG. 11N) used to form memory device1100 can be used to form memory device 1300 of FIG. 13. For example, theelements of memory device 1300 in FIG. 13 are the same as the elementsof memory device 1100 of FIG. 11N. As shown in FIG. 13, memory device1300 has no voids. Thus, the process of forming voids (e.g., voids 1185in FIG. 11P) can be omitted from the processes of forming memory device1300. After the structure of memory device 1300 shown in FIG. 13 isformed, additional processes can be used to complete memory device 1300.After completion, memory device 1300 can include elements similar tomemory device 100 (FIG. 1) and memory device 200 (FIG. 2A through FIG.2E, except for voids). As shown in FIG. 13, memory device 1300 includeselements that are similar to or identical to memory device 500A (FIG.5A). Thus, the processes used to form memory device 1300 can also beused to form memory device 500A.

FIG. 14 shows cross-sectional views of elements during processes offorming memory device 1400, according to some embodiments describedherein. Memory device 1400 can be a variation of memory device 1300 ofFIG. 13. Thus, some of the processes (e.g., the process described abovewith reference to FIG. 11A through FIG. 11N) used to form memory device1100 can be used to form memory device 1400 of FIG. 14. For example, theelements of memory device 1400 in FIG. 14 are the same as the elementsof memory device 1100 of FIG. 11N except that memory device 1400 has novoids. Thus, the process of forming voids (e.g., voids 1185 in FIG. 11P)can be omitted from the processes of forming memory device 1400.Further, as shown in FIG. 14, memory device 1400 can include dielectricmaterials 622′ (e.g., silicon oxide), whereas memory device 1100 in theprocesses associated with FIG. 11N include dielectric material 624′(e.g., silicon nitride). Thus, forming memory device 1400 can includethe processes of forming memory device 1100 with a modification. Forexample, memory cell structures and gates 683 of memory device 1400 canbe formed in the levels where dielectric materials 624 (e.g., siliconnitride, which can be similar to dielectric materials 624′ in FIG. 11A)were formed. Thus, as shown in FIG. 14, dielectric materials 622′ (e.g.,silicon oxide) can be a remaining portion of dielectric materials 622(e.g., silicon oxide, which can be similar to dielectric materials 622′in FIG. 11A).

In FIG. 14, after the structure of memory device 1400 shown in FIG. 14is formed, additional processes can be used to complete memory device1400. After completion, memory device 1400 can include elements similarto memory device 100 (FIG. 1) and memory device 200 (FIG. 2A throughFIG. 2E, except for voids). As shown in FIG. 14, memory device 1400includes elements that are similar to or identical to memory device 500B(FIG. 5B). Thus, the processes used to form memory device 1400 can alsobe used to form memory device 500B.

FIG. 15 is a flow chart showing a method 1500 of forming a memorydevice, according to some embodiments described herein. Method 1500 canbe used to form the memory devices described above with reference toFIG. 1 through FIG. 14. As shown in FIG. 15, activity 1510 of method1500 can include forming a first memory cell structure on a first levelof a memory device. Activity 1520 can include forming a first gate onthe first level of the memory device. Activity 1530 can include forminga second memory cell structure on a second level of the memory device.Activity 1540 can include forming a second gate on the second level ofthe memory device. Activity 1550 can include forming a void between thefirst and second gate and between the first and second memory cellstructures.

Method 1500 described above can include fewer or more activitiesrelative to activities 1510, 1520, 1530, 1540, and 1550 shown in FIG.15. For example, method 1500 can include processes of forming the memorydevices described above with reference to FIG. 2A through FIG. 14.

The illustrations of apparatuses (e.g., memory devices 100, 200, 300A,300B, 300C, 300D, 300E, 400A, 400B, 500A, 500B, 600, 700, 800, 900,1000, 1100, 1200, 1300, and 1400) and methods (e.g., processesassociated with forming memory devices 200, 300A, 300B, 300C, 300D,300E, 400A, 400B, 500A, 500B, 600, 700, 800, 900, 1000, 1100, 1200,1300, and 1400, and method 1500) are intended to provide a generalunderstanding of the structure of various embodiments and are notintended to provide a complete description of all the elements andfeatures of apparatuses that might make use of the structures describedherein. An apparatus herein refers to, for example, either a device(e.g., any of memory devices 100, 200, 300A, 300B, 300C, 300D, 300E,400A, 400B, 500A, 500B, 600, 700, 800, 900, 1000, 1100, 1200, 1300, and1400) or a system (e.g., a computer, a cellular phone, or otherelectronic systems) that includes a device such as any of memory devices100, 200, 300A, 300B, 300C, 300D, 300E, 400A, 400B, 500A, 500B, 600,700, 800, 900, 1000, 1100, 1200, 1300, and 1400.

Any of the components described above with reference to FIG. 1 throughFIG. 15 can be implemented in a number of ways, including simulation viasoftware. Thus, apparatuses, e.g., memory devices 100, 200, 300A, 300B,300C, 300D, 300E, 400A, 400B, 500A, 500B, 600, 700, 800, 900, 1000,1100, 1200, 1300, and 1400, or part of each of these memory devicesdescribed above, may all be characterized as “modules” (or “module”)herein. Such modules may include hardware circuitry, single- and/ormulti-processor circuits, memory circuits, software program modules andobjects and/or firmware, and combinations thereof, as desired and/or asappropriate for particular implementations of various embodiments. Forexample, such modules may be included in a system operation simulationpackage, such as a software electrical signal simulation package, apower usage and ranges simulation package, a capacitance-inductancesimulation package, a power/heat dissipation simulation package, asignal transmission-reception simulation package, and/or a combinationof software and hardware used to operate or simulate the operation ofvarious potential embodiments.

Memory devices 100, 200, 300A, 300B, 300C, 300D, 300E, 400A, 400B, 500A,500B, 600, 700, 800, 900, 1000, 1100, 1200, 1300, and 1400 may beincluded in apparatuses (e.g., electronic circuitry) such as high-speedcomputers, communication and signal processing circuitry, single- ormulti-processor modules, single or multiple embedded processors,multicore processors, message information switches, andapplication-specific modules including multilayer, multichip modules.Such apparatuses may further be included as subcomponents within avariety of other apparatuses (e.g., electronic systems), such astelevisions, cellular telephones, personal computers (e.g., laptopcomputers, desktop computers, handheld computers, tablet computers,etc.), workstations, radios, video players, audio players (e.g., MP3(Motion Picture Experts Group, Audio Layer 3) players), vehicles,medical devices (e.g., heart monitor, blood pressure monitor, etc.), settop boxes, and others.

The embodiments described above with reference to FIG. 1 through FIG. 15include apparatuses, and methods of forming the apparatuses. One of theapparatuses includes a channel to conduct current, the channel includinga first channel portion and a second channel portion, a first memorycell structure located between a first gate and the first channelportion, a second memory cell structure located between a second gateand the second channel portion, and a void located between the first andsecond gates and between the first and second memory cell structures.Other embodiments including additional apparatuses and methods aredescribed.

In the detailed description and the claims, a list of items joined bythe term “at least one of” can mean any combination of the listed items.For example, if items A and B are listed, then the phrase “at least oneof A and B” means A only; B only; or A and B. In another example, ifitems A, B, and C are listed, then the phrase “at least one of A, B andC” means A only; B only; C only; A and B (excluding C); A and C(excluding B); B and C (excluding A); or all of A, B, and C. Item A caninclude a single element or multiple elements. Item B can include asingle element or multiple elements. Item C can include a single elementor multiple elements.

In the detailed description and the claims, a list of items joined bythe term “one of” can mean only one of the list items. For example, ifitems A and B are listed, then the phrase “one of A and B” means A only(excluding B), or B only (excluding A). In another example, if items A,B, and C are listed, then the phrase “one of A, B and C” means A only; Bonly; or C only. Item A can include a single element or multipleelements. Item B can include a single element or multiple elements. ItemC can include a single element or multiple elements.

The above description and the drawings illustrate some embodiments ofthe inventive subject matter to enable those skilled in the art topractice the embodiments of the inventive subject matter. Otherembodiments may incorporate structural, logical, electrical, process,and other changes. Examples merely typify possible variations. Portionsand features of some embodiments may be included in, or substituted for,those of others. Many other embodiments will be apparent to those ofskill in the art upon reading and understanding the above description.

What is claimed is:
 1. A method comprising: forming an opening through afirst dielectric material, a second dielectric material, and a thirddielectric material, the second dielectric material being between thefirst and third dielectric materials; forming a first recess in thefirst dielectric material; forming a second recess in the thirddielectric material; forming a dielectric material in each of first andsecond recesses, the dielectric material having a dielectric constantgreater than a dielectric constant of silicon dioxide; removing aportion of the dielectric material and leaving a first remaining portionof the dielectric material in the first recess, and a second remainingportion of the dielectric material in the second recess; forming amemory element in each of the first and second recesses; forming a firstgate contacting the first remaining portion of the dielectric material;and forming a second gate contacting the second remaining portion of thedielectric material.